A silicon carbide (SiC) is expected as a material for a next-generation semiconductor device. Silicon carbide has the characteristics that the bandgap of the silicon carbide is three times wider than that of silicon (Si), the breakdown field strength of the silicon carbide is about ten times higher than that of silicon, and the thermal conductivity of the silicon carbide is about three times higher than that of silicon. The use of the characteristics makes it possible to achieve a semiconductor device that has low loss and can operate at a high temperature.
However, for example, in a case in which a metal oxide semiconductor field effect transistor (MOSFET) is formed using silicon carbide, there is a problem that the mobility of carriers is reduced. It is considered that one of the causes of the reduction in the mobility of carriers is an interface state (surface state) present in an interface between a silicon carbide layer and a gate insulating layer.